1. Field of the Invention
This invention generally relates to orally administrable pharmaceutical compositions and more particularly to dexibuprofen-containing soft gelatin capsules.
2. Description of the Related Art
The insolubility of solid drug forms in common media such as water poses a major challenge because of the resulting low bioavailability of the active ingredients. Liquid dosage forms, in contrast, generally have better bioavailability. One such liquid form is the soft gelatin, or softgel, capsule. Patient compliance is with softgel formulations is improved because soft gelatin capsules"" soft, elastic character make them easier swallow than conventional tablets or hard gelatin capsules. Furthermore, since the dosage form is generally swallowed, it is unnecessary to flavor or otherwise mask any unpleasant taste of the active pharmaceutical ingredients. Finally unlike tablets, soft gelatin capsules do not chip or powder.
Another drug delivery issue is content uniformity. If a formulation is a true solution, content uniformity can be achieved. The active ingredient may be completely dissolved in a softgel formulation.
Dexibuprofen is a non-steroidal anti-inflammatory (NSAID), analgesic (pain relieving), and antipyretic (fever reducing) drug. NSAID is a general term for a specific group of drugs, which effectively reduce inflammation and pain. NSAIDs inhibit the body""s production of prostaglandins and other compoundsxe2x80x94such as cyclooxygenase, lipoxygenase, leukotrienes, and lysosomal enzymesxe2x80x94that sensitize pain receptors and stimulate inflammatory responses. NSAIDs are generally absorbed into the bloodstream. Pain and fever relief usually occurs within 1 hour of taking the first dose and can last up to 6 hours. The anti-inflammatory effect of these agents generally takes longer to work (several days to 2 weeks) and may take a month or more to reach maximum effect (Physician ""s Desk Reference, 53rd ed., 1667-76 (1999)).
Dexibuprofen is also known as (S)-(+)-2-(4-isobutylphenyl)propionic acid or (S)-ibuprofen. It is practically insoluble in water, but is freely soluble in methanol, methylene chloride, and acetone. Dexibuprofen is readily soluble in most organic solvents and is soluble in aqueous solutions of alkali hydroxides and-carbonates (Martindale, 32nd ed., K. Parfitt ed., 44).
Dexibuprofen is an effective non-steroidal, anti-inflammatory drug with a significant dose response relationship in patients with painful osteoarthritis of the hip. Compared with racemic ibuprofen, half of the daily dose of dexibuprofen shows at least equivalent efficacy (F. Singer, et al., Int. J. Clin. Pharm. Ther., 38(J), 25-29 (2000)). Dexibuprofen is practically water insoluble, however, raising the issue of bioavailability.
Ibuprofen containing soft gelatin capsules are known. U.S. Pat. No. 4,690,823 to Lohner et al. describes soft gelatin capsules containing, by weight, a solution of 15 to 30 parts of ibuprofen in 70 to 85 parts of polyoxyethylene-polyoxypropylene polymer, or a mixture of 30 to 76 parts of polyalkylene glycol and 7 to 40 parts of a surfactant. These softgels exhibit very rapid and high bioavailability of the active ingredient. The active ingredient is not reprecipitated by aqueous media such as artificial gastric juice.
Gelatin-sheath-enclosed liquid softgel formulations containing ibuprofen as the free acid are described in U.S. Pat. No. 6,251,426 to Gullapalli. The softgels are prepared by dissolving greater than 30% by weight of ibuprofen free acid in polyethylene glycol and at least 10% of polyvinylpyrrolidone of an average molecular weight of about 2,000 to 54,000. These formulations may also include a surfactant to increase the bioavailability of the ibuprofen.
U.S. Pat. No. 6,255,347 to Xiaotao et al. describes the use of the R-enantiomer of ibuprofen, previously thought inactive. Particularly, Xiaotao et al. discloses that (R)-ibuprofen, is an antineoplastic agent, and also a prophylactic and therapeutic treatment of Alzheimer""s and Alzheimer""s related diseases.
European Patent Application EP0439344 describes an ibuprofen-containing, topical, hydroalcoholic gel for treating inflammation or pain. Corresponding U.S. Pat. No. 5,093,133 describes an ibuprofen-containing, topical, hydroalcoholic gel for treating inflammation or pain, methods for delivering ibuprofen through the skin to treat inflammation or pain using this gel; and using (S)-ibuprofen topically to treat inflammation or pain.
U.S. Pat. No. 5,869,102 describes a solid pharmaceutical composition containing (S)-ibuprofen as the active ingredient. These compositions are suitable for the preparation of tablets, sachets and capsules. The tablets contain (S)-ibuprofen, colloidal silica, microcrystalline cellulose, and magnesium stearate. Tablets are prepared by direct compression of the pharmaceutical composition and may be coated or filmed according to conventional techniques.
Accordingly, we sought to devise a soft gelatin capsule formulation of dexibuprofen. Because the dexibuprofen in this formulation is predissolved in the softgel, it may be more bioavailable compared to solid dexibuprofen.
In accordance with one preferred embodiment, there are provided formulations of substantially clear solutions of dexibuprofen. More specifically, preferred pharmaceutical formulations disclosed herein comprise a substantially clear dexibuprofen solution containing about 40% by weight of dexibuprofen, about 40% by weight of a solubilizer, about 0.8% to 5% by weight of surfactants, about 14% to 20% by weight of co-surfactants, about 2% by weight of a potassium salt generating species, and about 2% by weight of a viscosity imparter.
In accordance with another preferred embodiment, there are provided soft gelatin capsules of dexibuprofen made from a pharmaceutical formulation comprising a substantially clear dexibuprofen solution containing about 40% by weight of dexibuprofen, about 40% by weight of a solubilizer, about 0.8% to 5% by weight of surfactants, about 14% to 20% by weight of co-surfactants, about 2% by weight of a potassium salt generating species, and about 2% by weight of a viscosity imparter.
In accordance with yet another preferred embodiment, there are provided methods of making these dexibuprofen-containing soft gelatin capsules, which comprise a substantially clear dexibuprofen solution containing about 40% by weight of dexibuprofen, about 40% by weight of a solubilizer, about 0.8% to 5% by weight of surfactants, about 14% to 20% by weight of co-surfactants, about 2% by weight of a potassium salt generating species, and about 2% by weight of a viscosity imparter.
A preferred solubilizer is diethylene glycol monoethyl ether. Preferred surfactants are caprylocaproyl macrogolglycerides or polyoxyethylene castor oil derivatives. Particularly preferred polyoxyethylene castor oil derivatives are polyoxyl(40) hydrogenated castor oil or polyoxyl(35) hydrogenated castor oil. A preferred co-surfactant is polyethylene glycol 400. A preferred potassium salt generating species is potassium hydroxide. A preferred viscosity imparter is polyvinylpyrrolidone. A particularly preferred viscosity imparter is povidone (PVP K-30).
One advantage of preferred embodiments is that the high solubility of dexibuprofen in diethyleneglycol monoethylether allows the production of softgels of acceptable sizes. In the present invention the dexibuprofen in the softgel is present as both the potassium salt and the free acid.
The present invention relates to dexibuprofen solutions in soft gelatin capsules. We conducted solubility studies on various solvents including polyethylene glycol, propylene glycol, alcohol, and diethylene glycol monoethyl ether. We discovered that dexibuprofen dissolved in diethylene glycol monoethyl ether (Transcutol(copyright) P, Gattefossxc3xa9) in a better than 1:1 ratio without heating.
Preferred formulations use diethyleneglycol monoethylether, a powerful solubilizing agent, to dissolve the dexibuprofen. Highly purified diethyleneglycol monoethylether is commercially available as Transcutol(copyright) P (Gattefossxc3xa9). Diethyleneglycol monoethylether solubilizes drugs that are commonly thought to be insoluble or difficult to solubilize (European Pharmacopoeia). It is soluble in water, ethanol, hexylene glycol, and propylene glycol, and is partially soluble in vegetable oils (Transcutol Product Profile, Gattefossxc3xa9, 1-9).
Preferred formulations contain caprylocaproyl macrogolglycerides (Labrasol(copyright), Gattefossxc3xa9), which is a mixture of mono-, di-, and triglycerides, and mono- and diesters of macrogols with a mean molecular weight of about 200 to 400 (British Pharmacopoeia; European Pharmacopoeia, 1184 (1998, corrected 2001)). The caprylocaproyl macrogolglycerides act as surfactants, emulsifying the formulation when exposed to aqueous media thereby enhancing the bioavailability of dexibuprofen.
Polyoxyl(40) hydrogenated castor oil or polyoxyl(35) hydrogenated castor oil may be used as surfactants in place of caprylocaproyl macrogolglycerides. These compounds are commercially available as Cremophor RH 40 and Cremophore RH 35 (BASF). Polyoxyethylene castor oil derivatives are complex mixtures of various hydrophobic and hydrophilic components. About 75% of the components are hydrophobic, and are composed mainly of fatty acid esters of glycerol polyethylene glycols, and fatty acid esters of polyethylene glycol. The hydrophilic portion consists of polyethylene glycol and glycerol ethoxylates. Polyoxyl(40) hydrogenated castor oil is a slightly opalescent liquid, whereas polyoxyl(35) hydrogenated castor oil is a clear liquid. Polyoxyl(40) hydrogenated castor oil has an HLB value of 11 to 14 (A. Wade, P.J. Weller, Handbook of Pharmaceutical Excipients, 2nd ed., 371 (1994)).
We have found polyethylene glycol 400 useful in the formulation as cosurfactant to aid the emulsification. Polyethylene glycols have been used to enhance the aqueous solubility or dissolution characteristics of poorly soluble drugs (A. Wade, P.J. Weller, Handbook of Pharmaceutical Excipients, 2nd ed., 355-61, (1994)).
The softgel formulation preferably also contains polyvinylpyrrolidone (povidone, PVP). Povidone (PVP K-30) has been used in a variety of pharmaceutical formulations. Polyvinylpyrrolidone with molecular weight of from about 2500 to 50,000 is preferred. Povidone is known to prevent dexibuprofen from precipitating (A. Wade, P. J. Weller, Handbook of Pharmaceutical Excipients, 2nd ed., 392401 (1994)). It also imparts viscosity to the solution, which aids in filling the drug delivery device, in this case a soft gelatin capsule.
One preferred embodiment discloses soft gelatin capsules in which the dexibuprofen is present as both the potassium salt and the free acid. Potassium hydroxide was used to convert dexibuprofen into its potassium salt. Because salts of acids are known to dissolve better in aqueous solution than the corresponding free acid, using the salt should improve the bioavailability of the dexibuprofen. Those skilled in the art will recognize that other compounds, for example potassium carbonate or potassium bicarbonate, could be used to generate the potassium salt of dexibuprofen. Also, cations other than potassium, including other monovalent cations, divalent and polyvalent cations, or organic cations, are within the scope of the present invention.
Preferred embodiments are further illustrated in the following examples.